3D packages and methods for forming the same

ABSTRACT

Embodiments of the present disclosure include a semiconductor device and methods of forming a semiconductor device. An embodiment is a method of forming a semiconductor device, the method comprising forming a conductive pad in a first substrate, forming an interconnecting structure over the conductive pad and the first substrate, the interconnecting structure comprising a plurality of metal layers disposed in a plurality of dielectric layers, bonding a die to a first side of the interconnecting structure, and etching the first substrate from a second side of the interconnecting structure, the etching exposing a portion of the conductive pad.

This application is a continuation and claims the benefit of U.S. patentapplication Ser. No. 13/938,939, filed on Jul. 10, 2013, and entitled“3D Packages and Methods for Forming the Same,” which claims the benefitof U.S. Provisional Application No. 61/786,031, filed on Mar. 14, 2013,and entitled “3D Packages and Methods for Forming the Same,” whichapplications are hereby incorporated by reference.

CROSS REFERENCE TO RELATED APPLICATION

The present application is related to co-pending U.S. patent applicationSer. No. 13/763,335, filed on Feb. 8, 2013, entitled “3D Packages andMethods for Forming the Same,” and commonly assigned to the assignee ofthe present application, which application is hereby incorporated byreference herein.

BACKGROUND

Since the invention of the integrated circuit (IC), the semiconductorindustry has experienced rapid growth due to continuous improvements inthe integration density of various electronic components (i.e.,transistors, diodes, resistors, capacitors, etc.). For the most part,this improvement in integration density has come from repeatedreductions in minimum feature size, which allows more components to beintegrated into a given area.

These integration improvements are essentially two-dimensional (2D) innature, in that the volume occupied by the integrated components isessentially on the surface of the semiconductor wafer. Although dramaticimprovement in lithography has resulted in considerable improvement in2D IC formation, there are physical limits to the density that can beachieved in two dimensions. One of these limits is the minimum sizeneeded to make these components. In addition, when more devices are putinto one chip or die, more complex designs are required.

In an attempt to further increase circuit density, three-dimensional(3D) ICs have been investigated. In a typical formation process of a 3DIC, two or more dies or chips are bonded together and electricalconnections are formed between each die or chip and contact pads on asubstrate.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present embodiments, and theadvantages thereof, reference is now made to the following descriptionstaken in conjunction with the accompanying drawings, in which:

FIG. 1 illustrates a flow diagram of a method for manufacturing asemiconductor device according to an embodiment;

FIGS. 2A through 2G illustrate intermediate stages of forming asemiconductor device according to an embodiment;

FIGS. 3A through 3C illustrate intermediate stages of forming asemiconductor device according to an embodiment;

FIG. 4A through 4B illustrate intermediate stages of forming asemiconductor device according to an embodiment;

FIG. 5 illustrates a semiconductor device according to an embodiment;

FIG. 6 illustrates a flow diagram of a method for manufacturing asemiconductor device according to an embodiment; and

FIGS. 7A through 7C illustrate intermediate stages of forming asemiconductor device according to an embodiment.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

Reference will now be made in detail to embodiments illustrated in theaccompanying drawings. Wherever possible, the same reference numbers areused in the drawings and the description to refer to the same or likeparts. In the drawings, the shape and thickness may be exaggerated forclarity and convenience. This description will be directed in particularto elements forming part of, or cooperating more directly with, methodsand apparatus in accordance with the present disclosure. It is to beunderstood that elements not specifically shown or described may takevarious forms well known to those skilled in the art. Many alternativesand modifications will be apparent to those skilled in the art, onceinformed by the present disclosure.

Reference throughout this specification to “one embodiment” or “anembodiment” means that a particular feature, structure, orcharacteristic described in connection with the embodiment is includedin at least one embodiment. Thus, the appearances of the phrases “in oneembodiment” or “in an embodiment” in various places throughout thisspecification are not necessarily all referring to the same embodiment.Furthermore, the particular features, structures, or characteristics maybe combined in any suitable manner in one or more embodiments. It shouldbe appreciated that the following figures are not drawn to scale;rather, these figures are merely intended for illustration.

Embodiments will be described with respect to a specific context, namelya semiconductor device with an interconnecting structure without asubstrate and without through substrate vias. Other embodiments may alsobe applied, however, to other interconnecting structures.

In a formation process of a 3D IC, two or more dies or chips are bondedtogether and electrical connections are formed between each die or chipand contact pads on a substrate. For example, interposer stacking ispart of 3D IC technology, where a through substrate via (TSV) embeddedinterposer is connected to a device chip or die with a micro bump.Interposer stacking manufacturing process flows can be separated into atleast two types. In a first type, a chip-on-chip-on-substrate (CoCoS)process flow, a silicon interposer chip is first mounted onto apackaging substrate, and then a different device silicon chip is bondedonto the interposer. In a second type, a chip-on-wafer-on-substrate(CoWoS) process flow, a device silicon chip is first bonded onto asilicon interposer wafer, which is then diced. The resulting stackedsilicon is then mounted onto a substrate.

FIG. 1 illustrates a flow diagram of a method 200 for manufacturing asemiconductor device in accordance with an embodiment. While method 200is illustrated and described below as a series of acts or events, itwill be appreciated that the illustrated ordering of such acts or eventsare not to be limited to a particular embodiment. For example, some actsmay occur in different orders and/or concurrently with other acts orevents apart from those illustrated and/or described herein. Inaddition, not all illustrated acts may be required to implement one ormore aspects or embodiments of the description herein. Further, one ormore of the acts depicted herein may be carried out in one or moreseparate acts and/or phases.

The operations of method 200 will be described with reference to FIGS.2A through 2G as an example, although the method 200 may be applied toother embodiments. At operation 202, a conductive pad is formed in afirst substrate. Operation 202 is illustrated in FIG. 2A as illustratedbelow.

Referring to FIG. 2A, a semiconductor device 10 at an intermediate stageof processing is illustrated. The semiconductor device 10 includes aconductive pads 22 in a top surface of a first substrate 20, apassivation layer 26 formed on the first substrate 20 and the conductivepads 22, and pad connectors 24 formed through the passivation layer 26and in contact with the conductive pads 22.

The first substrate 20 may be formed of a semiconductor material, suchas silicon, silicon germanium, silicon carbide, gallium arsenide, orother commonly used semiconductor materials. Alternatively, the firstsubstrate 20 is formed of a dielectric material, such as glass, aluminumoxide, aluminum nitride, the like, or a combination thereof. The firstsubstrate 20 is free from active devices (such as transistors anddiodes) and passive devices (such as inductors, resistors, andcapacitors).

The conductive pads 22 may be formed in a top surface of the firstsubstrate 20. The conductive pads may be formed by forming recesses (notshown) into the first substrate 20. The recesses may be formed into thefirst substrate 20 to allow the conductive pads 22 to be embedded intothe substrate 20. These embedded conductive pads 22 may act as underbumpmetallizations after the first substrate 20 is removed throughsubsequent processing. (see FIG. 2E). The recesses may be formed using asuitable photolithographic mask and etching process, although anysuitable process to form recesses allowing the embedding of theconductive pads 22 may be used.

After the recesses are formed in the first substrate 20, the recessesmay be filled with a conductive material to form the conductive pads 22.In some embodiments, a barrier layer (not shown) may be formed in therecesses to help to block diffusion of the subsequently formedconductive pads 22 into the adjacent substrate 20. The barrier layer(not shown) may comprise titanium, titanium nitride, tantalum, tantalumnitride, manganese, manganese oxide, cobalt, cobalt oxide, cobaltnitride, the like, or a combination thereof and 28 may be formed bychemical vapor deposition (CVD), physical vapor deposition (PVD), plasmaenhanced CVD (PECVD), atomic layer deposition (ALD), the like, or acombination thereof to a thickness from about 5 Å to about 200 Å.

The conductive material may be formed by an electro-chemical platingprocess, sputtering, CVD, ALD, PVD, the like, or a combination thereof.In an embodiment, the conductive material of the conductive pads 22 maycomprise copper, tungsten, aluminum, silver, gold, the like, or acombination thereof. After the conductive material is formed in therecesses (not shown), the conductive material may be planarized by aplanarization process, such as a chemical mechanical polishing (CMP)process. In an embodiment, the conductive pads 22 have a thickness in arange from about 5.0 kÅ to about 30.0 kÅ. In some embodiments, the topsurfaces of the conductive pads 22 may be substantially coplanar with atop surface of the substrate 20.

At operation 204, a passivation layer is formed on the conductive padand the first substrate. Operation 204 is illustrated in FIG. 2A asdescribed below.

The passivation layer 26 is formed on the conductive pads 22 and thefirst substrate 20. The passivation layer 26 can be silicon nitride,silicon carbide, silicon oxide, low-k dielectrics such as carbon dopedoxides, extremely low-k dielectrics such as porous carbon doped silicondioxide, a polymer, such as an epoxy, polyimide, benzocyclobutene (BCB),polybenzoxazole (PBO), the like, or a combination thereof, althoughother relatively soft, often organic, dielectric materials can also beused, and deposited by chemical vapor deposition (CVD), physical vapordeposition (PVD), atomic layer deposition (ALD), a spin-on-dielectricprocess, the like, or a combination thereof. In some embodiments, thepassivation layer 26 is a polymer such as polyimide.

After the passivation layer 26 is formed, pad connectors 24 may beformed through the passivation layer 26 and in contact with theconductive pads 22. The pad connectors allow for electrical and physicalcoupling between conductive pads 22 and subsequently formedinterconnecting structure 30. The pad connectors 24 may be formed byforming openings (not shown) to expose portions of the conductive pads22. The openings may be formed into the passivation layer 26 to allowthe pad connectors 24 to be embedded into the passivation layer 26. Theopenings may be formed using a suitable photolithographic mask andetching process, although any suitable process to form openings allowingthe embedding of the pad connectors 24 may be used.

After the openings (not shown) are formed, a conductive material may beformed in the openings to form the pad connectors 24. The forming of theof the pad connectors 24 may include a barrier layer and a conductivematerial similar to conductive pads 22, although the pad connectors 24and the conductive pads 22 materials need not be the same.

At operation 206, an interconnecting structure is formed over thepassivation layer and the conductive pads. Operation 206 is illustratedin FIGS. 2B and 2C as described below.

Referring to FIG. 2B, an interconnecting structure 30 is formed on thepassivation layer 26 and the pad connectors 24, a die 54 is bonded to afirst side 31 of the interconnecting structure 30 with connectors 50 onunder bump metallizations (UBMs) 46, and a molding compound 55 issurrounding the die 54 (see also FIG. 2C).

The interconnecting structure 30 comprises a plurality of thin filmlayers with a plurality of metal layers disposed therein. The pluralityof thin film layers include inter-metal dielectrics (IMDs) 38 and etchstop layers 32. The plurality of metal layers includes metal lines 36and vias 40. The metal lines 36 and vias 40 may electrically connect thedie 54 on a first side 31 of the interconnecting structure 30 with theconductive pads 22 on a second side 33 which may be connected to variousdevices and/or substrates to form functional circuitry (see FIG. 2I).The IMDs 38 may be formed of oxides such as silicon oxide,borophosphosilicate glass (BPSG), undoped silicate glass (USG),fluorinated silicate glass (FSG), low-k dielectric materials, the like,or a combination thereof. Different respective IMDs may comprisedifferent materials. The low-k dielectric materials may have k valueslower than 3.9. In some embodiments, the low-k dielectric materials havea k value less than 3.0 or even less than 2.5. In some otherembodiments, the low-k dielectric materials have a k value less than2.0. The etch stop layers 32 can be silicon nitride, silicon carbide,silicon oxide, low-k dielectrics such as carbon doped oxides, extremelylow-k dielectrics such as porous carbon doped silicon dioxide, the like,or a combination thereof, and deposited by CVD, PVD, ALD, aspin-on-dielectric process, the like, or a combination thereof.Conductive materials, such as copper, aluminum, titanium, the like, or acombination thereof, with or without a barrier layer, can be used as themetal lines 36 and the vias 40. In an embodiment, each of the metallayers M1 through Mn has a thickness in a range from about 5.0 kÅ toabout 30.0 kÅ.

Interconnecting structure 30 includes a plurality of metal layers,namely M1, M2, M3, and Mn, wherein metal layer M1 is the metal layerdirectly connected to the pad connectors 24, while metal layers M2 andM3 are intermediate layers above metal layer M1, and metal layer Mn isthe metal layer that is immediately under the overlying UBMs 46, whereinthe value n of Mn is greater than or equal to two. The metal layer Mnmay be referred to as a metal pad or a contact pad. Throughout thedescription, the term “metal layer” refers to the collection of themetal lines in the same layer, and the term “metal layer” does notinclude a through substrate via (TSV). Metal layers M1 through Mn areformed in the IMDs 38. In an embodiment, the metal lines 36 are formedto have a width from about 0.8 um to about 30 um with a spacing betweenadjacent metal lines 36 from about 0.8 um to about 30. In someembodiments the metal lines 36 are formed to have a width from about 0.4um to about 5 um with a spacing between adjacent metal lines from about0.4 um to about 5 um.

As illustrated in FIG. 2B, the interconnecting structure 30 may comprisea first portion 30A and a second portion 30B. The first portion 30A hasa non-continuous metal line 36 of the metal layer M1, and the secondportion 30B has metal pad in the metal line 36 of metal layer M1 thatmay be larger than the metal lines 36 in the other layers. In otherembodiments, other layers M2 through Mn may have metal lines 36 that arelarger metal lines 36 in metal layer M1. In some embodiments, both thefirst and second portions 30A and 30B may comprise metal pads in themetal lines 36 of metal layer M1 and each may have connectors formed themetal pads (see FIGS. 7A through 6D).

In an embodiment, the metal line 36 of metal layer M1 has a surfacesubstantially coplanar with the second side 33 of the interconnectingstructure 30, and the metal line 36 of the metal layer Mn has a surfacesubstantially coplanar with the first side 31 of the interconnectingstructure 30. There may be ten vias 40 or up to N vias 40 connecting theadjacent metal lines 36 rather than the two vias 40 illustrated in FIG.2B. The large number of vias 40 in each metal layer may be used to lowerthe resistance between the connectors 50 and the connectors 68 (see FIG.2H), to improve heat dissipation in the interconnecting structure 30,and/or for structural support in the interconnecting structure 30.

The metal layers, M1, M2, M3, and Mn may be formed using a single and/ora dual damascene process, a via-first process, or a metal-first process.Damascene means formation of a patterned layer embedded in another layersuch that the top surfaces of the two layers are coplanar. A damasceneprocess which creates either only trenches or vias is known as a singledamascene process. A damascene process which creates both trenches andvias at once is known as a dual damascene process.

In an exemplary embodiment, the metal layers M1 through Mn are formedusing a dual damascene process. In this example, the formation of the M1layer may begin with the formation of an etch stop layer 32 on thepassivation layer 26 and the pad connectors 24 with an IMD 38 on theetch stop layer 32. Once the IMD 38 is deposited, portions of the IMD 38may be etched away to form recessed features, such as trenches and vias,which can be filled with conductive material to connect differentregions of the interconnecting structure 30 and accommodate the metallines 36 and vias 40. This process may be repeated for the remainingmetal layers M2 through Mn.

The number of metal layers M1 to Mn, the number of IMDs 38, the numberof vias 40, and the number of metal lines 36 are only for illustrativepurposes and are not limiting. There could be other number of layersthat is more or less than the four metal layers illustrated. There maybe other number of IMD layers, other number of vias, and other number ofmetal lines different from those illustrated in FIG. 2B.

In some embodiments, the vias 40 of the adjacent metal layers are notaligned (offset) from the vias 40 of a metal layer Mn and the vias 40 ofdifferent layers may be a different size than vias 40. In someembodiments, all the metal layers, M1 through Mn, are substantiallyvertically aligned. In some embodiments, a top surface area of the metallines 36 in each of the metal layers may be substantially equal to eachof the other metal layers of the interconnecting structure 30. In otherembodiments, the metal layers M1 through Mn are not aligned and havedifferent top surface areas. The vias 40 and the metal lines may be anysuitable shape such as, a square, a circle, a rectangle, a hexagon,other polygons, or the like.

At operation 208, a die is bonded to a first side of the interconnectingstructure. Operation 208 is illustrated in FIG. 2B as described below.

Referring back to FIG. 2B, after the formation of the interconnectingstructure 30, a first passivation layer 41 and a second passivationlayer 42 may be formed to cover and protect the metal lines 36 and theinterconnecting structure 30. The first and second passivation layers 41and 42 may be similar to the passivation layer 26 discussed above andwill not be repeated herein, although the passivation layer 26 and thefirst and second passivation layers 41 and 42 need not be the same.

After the formation of the second passivation layer 42, openings may beformed through the second passivation layer 42 and the first passivationlayer 41 to expose portions of the metal lines 36 of metal layer Mn. Theopenings allow for electrical and physical coupling between metal lines36 of metal layer Mn of the interconnecting structure 30 and thesubsequently formed UBMs 46. These openings may be formed using asuitable photolithographic mask and etching process, although anysuitable process to expose portions of the metal lines 36 of metal layerMn may be used.

After the openings are formed through the first and second passivationlayers 41 and 42, the UBMs 46 may be formed along the second passivationlayer 42 and in the openings over the metal lines 36 of metal layer Mn.In an embodiment the UBMs 46 may comprise three layers of conductivematerials, such as a layer of titanium, a layer of copper, and a layerof nickel. However, one of ordinary skill in the art will recognize thatthere are many suitable arrangements of materials and layers, such as anarrangement of chrome/chrome-copper alloy/copper/gold, an arrangement oftitanium/titanium tungsten/copper, or an arrangement ofcopper/nickel/gold, that are suitable for the formation of the UBM 46.Any suitable materials or layers of material that may be used for theUBMs 46 are fully intended to be included within the scope of thecurrent application.

The UBMs 46 may be created by forming each layer over the secondpassivation layer 42 and along the interior of the openings through thefirst and second passivation layers 41 and 42 to the metal lines 36 ofthe metal layer Mn. The forming of each layer may be performed using aplating process, such as electrochemical plating, although otherprocesses of formation, such as sputtering, evaporation, orplasma-enhanced CVD (PECVD) process, may alternatively be used dependingupon the desired materials. Once the desired layers have been formed,portions of the layers may then be removed through a suitablephotolithographic masking and etching process to remove the undesiredmaterial and to leave the UBMs 46 in a desired shape, such as acircular, octagonal, square, or rectangular shape, although any desiredshape may alternatively be formed.

After the UBMs 46 are formed, an active surface of the die 54, theactive surface comprising the connectors 50, is bonded to a first side31 of the interconnecting structure 30 by way of the connectors 50 andthe UBMs 46. The die 54 may be a device die comprising integratedcircuit devices, such as transistors, capacitors, inductors, resistors(not shown), and the like, therein. Further, the die 54 may be a logicdie comprising core circuits, and may be, for example, a centralprocessing unit (CPU) die. In some embodiments, the die 54 may comprisemultiple stacked dies like a memory stacking. The connectors 50 may bebonded to contacts or bond pads (not shown) on the die 54.

The connectors 50 are illustrated as micro bumps in FIG. 2B, however inother embodiments, the connectors 50 may be solder balls, metal pillars,controlled collapse chip connection (C4) bumps, electrolessnickel-electroless palladium-immersion gold technique (ENEPIG) formedbumps, or the like. The connectors 50 may comprise a conductive materialsuch as copper, aluminum, gold, nickel, silver, palladium, tin, thelike, or a combination thereof. In an embodiment in which the connectors50 are tin solder bumps, the connectors 50 may be formed by initiallyforming a layer of tin through such commonly used methods such asevaporation, electroplating, printing, solder transfer, ball placement,or the like. Once a layer of tin has been formed on the structure, areflow may be performed in order to shape the material into the desiredbump shape. In another embodiment the connectors 50 may be metal pillars(such as copper pillars), which may be pre-formed before the die 54 isplaced over the interconnecting structure 30. The metal pillars may beformed by a plating process and may be solder free and comprisesubstantially vertical sidewalls. In this embodiment, the UBMs 46 may beomitted as the metal pillars may extend from the metal lines 36 to thedie 54.

The bonding between the die 54 and the interconnecting structure 30 maybe a solder bonding or a direct metal-to-metal (such as acopper-to-copper or tin-to-tin) bonding. In an embodiment, the die 54may be bonded to the interconnecting structure 30 by a reflow process.During this reflow process, the connectors 50 are in contact with theUBMs 46 to physically and electrically couple the die 54 to theinterconnecting structure 30.

An underfill material 52 may be injected or otherwise formed in thespace between the die 54 and the interconnecting structure 30. Theunderfill material 52 may, for example, comprise a liquid epoxy,deformable gel, silicon rubber, or the like, that is dispensed betweenthe die 54 and the interconnecting structure 30, and then cured toharden. This underfill material 52 is used, among other things, toreduce cracking in and to protect the connectors 50.

A molding compound 55 may be formed surrounding the die 54 (see FIG. 2C)and on the underfill 52 and over a first side 31 of the interconnectingstructure 30. The molding compound may provide protection and rigidnessto the die 54 and the semiconductor device 10. In an embodiment, themolding compound 55 may be a nonconductive material, such as an epoxy, aresin, polyimide, polybenzoxazole (PBO), benzocyclobutene (BCB), asilicone, an acrylate, the like, or a combination thereof. The moldingcompound 55 may be formed to have a top surface over, substantiallylevel with, or a backside surface of the die 54.

As illustrated in FIG. 2C, in some embodiments, there may be a pluralityof semiconductor devices 10 formed adjacent each other on the firstsubstrate 20. The molding compound 55 surrounds the dies 54 and is onthe underfill 52 and portions of the interconnecting structures 30.

At operation 210, the first substrate 20 is thinned. Operation 210 isillustrated in FIG. 2D as described below.

FIG. 2D illustrates the thinning of the backside surface of the firstsubstrate 20. The thinning process may be performed using an etchingprocess, a chemical mechanical polishing (CMP) process, and/or aplanarization process, such as a grinding process. After the substrate20 is thinned, the substrate may have a thickness T2 which is less thanthe thickness T1 of the conductive pad 22 plus about 5 um. For example,if the conductive pad thickness T1 is 1 um, the thickness T2 of theremaining first substrate 20 less than 6 um.

At operation 212, the remaining portion of the first substrate isremoved. Operation 212 is illustrated in FIG. 2E as described below.

FIG. 2E illustrates the removal of the remaining portion of the firstsubstrate 20. The remaining portion of the first substrate 20 may beremoved by a wet etch process that is selective to the first substrate20 without attacking the conductive pads 22. In an embodiment, theselective wet etch comprises an etchant comprising tetramethylammoniumhydroxide (TMAH) as it enables selective crystallographic etching ofsilicon. In another embodiment, the selective wet etch comprises HF andHNO₃. In some embodiments, the wet etch process includes a corrosioninhibitor comprising benzotriazole (BTA), tolytriazole (TTA),triphenylmethane, the like, or a combination thereof. The selective wetetch removes the remaining portion of the first substrate 20 to exposethe conductive pads 22 and the passivation layer 26. In an embodiment,the interconnecting structure 30 has a thickness T3 in a range fromabout 3 μm to about 10 μm. In another embodiment, the interconnectingstructure 30 may have a thickness T3 in a range from about 3 μm to about30 μm.

The exposed conductive pads 22 may be used as UBMs for subsequentlyformed connectors (see FIGS. 2H, 3B, and 4) and may be referred to asUBMs 22. In some embodiments, the exposed conductive pads 22 may be usedas a conductive pillar and mounted to another device and/or substratewithout forming a connector on the conductive pad 22.

With the removal of the first substrate 20, the interconnectingstructure 30 may provide an interface and structure to couple the die 54on its first side 31 to one or more devices and/or substrates on itssecond side 33 via the UBMs 22. In some embodiments, the interconnectingstructure 30 is free from a substrate and is also free from throughsubstrate vias (TSVs). This provides for an interconnecting structure 30that may be thinner than a structure with a substrate and also aninterconnecting structure 30 that costs less to manufacture than astructure with TSVs. Further, the interconnecting structure 30 is moreflexible and can bend (warp) and may accommodate the stresses and forcesof subsequent processing (e.g. bonding the die 54 to the interconnectingstructure 30) better than a structure with a substrate.

At operation 214 a connector is formed over the second side of theinterconnecting structure. Operation 214 is illustrated in FIG. 2F asdescribed below.

In FIG. 2F, the semiconductor device 10 has been flipped over so thatthe die 54 and molding compound 55 are towards the bottom of the figure.The exposed conductive pads 22 may be used as the connector and directlymounted to another device and/or substrate without forming anotherconnector on the conductive pad 22. (see FIG. 2G).

At operation 216, a second side of the interconnecting structure may bebonded to a second substrate. Operation 216 is illustrated in FIG. 2G asdescribed below.

FIG. 2G illustrates bonding the second side 33 of the interconnectingstructure 30 to a second substrate 70 by way the conductive pads 22. Thesecond substrate 70 may be similar to the first substrate 20 asdescribed above, although the first substrate 20 and the secondsubstrate 70 need not be the same. Second substrate 70 is, in onealternative embodiment, based on an insulating core such as a fiberglassreinforced resin core. One example core material is fiberglass resinsuch as FR4. Alternatives for the core material includebismaleimide-triazine (BT) resin, or alternatively, other PC boardmaterials or films. Build up films such as Ajinomoto build-up film (ABF)or other laminates may be used for second substrate 70.

The second substrate 70 has contacts 58 which will be physically andelectrically coupled to the conductive pads 22. In some embodiments, thecontacts 58 may comprise a pre-solder layer, and in other embodiments,the contacts 58 may comprise a bond pad, or solder ball. The contacts 58may comprise solder, tin, silver, tin, the like, or a combinationthereof. In an embodiment, the second substrate 70 may be bonded to theinterconnecting structure 30 by a reflow process. During this reflowprocess, the contacts 58 on the second substrate 70 are in contact withthe conductive pads 22 to physically and electrically couple the secondsubstrate 70 to the interconnecting structure 30.

The number of conductive pads 22, the number of contacts 72, and thenumber of UBMs 46 in FIG. 2G are only for illustrative purposes and arenot limiting. There could be any suitable number of conductive pads 22,UBMs 46, and contacts 58.

FIGS. 3A through 3C illustrate plating a connector on the conductivepads 22 and bonding to a second substrate according to anotherembodiment. FIG. 3A illustrates the formation of a patterned photoresist64 on the passivation layer 26 and exposing the UBMs 22, a seed layer 62on the UBMs 22, and a conductive material 66 on the seed layer 62. Thephotoresist 64 may then be formed to UBMs 22, and the photoresist maythen be patterned to expose of the portions of the UBMs 22 where theconductive material 66 is desired to be located. In some embodiments,one or more barrier layers (not shown) may be formed on the UBM 22comprising titanium, titanium nitride, tantalum, tantalum nitride, thelike, or a combination thereof. The one or more barrier layers may beformed by CVD, PVD, PECVD, ALD, the like, or a combination thereof. Theseed layer 62 may comprise a titanium copper alloy or the like on theone or more barrier layers, if present, through CVD, sputtering, thelike, or a combination thereof. Once the seed layer 62 been formed andpatterned, the conductive material 66, such as copper, aluminum, gold,nickel, silver, tin, the like, or a combination thereof may be formed onthe seed layer through a deposition process such as plating, CVD, PVD,the like, or a combination thereof. In another embodiment, the seedlayer 62 may be formed before the photoresist 64 and patterned after thephotoresist 64 is removed using conductive material 66 as a mask.

FIG. 3B illustrates the removal of the photoresist 64 and the formationof the connector 68 from the conductive material 66. The photoresist 64may be removed through a suitable removal process such as ashing. Theconductive material 66 may be shaped to form connectors 68 with arounded top surface by performing a reflow process on the conductivematerial 66. In some embodiments, the connectors 68 may be substantiallyaligned with one of the UBMs 46 and connectors 50 in the first portion30A and/or the second portion 30B of the interconnecting structure 30 asillustrated in FIG. 3B.

In some embodiments, there may be a plurality of semiconductor devices10 formed adjacent each other on the first substrate 20 (see FIG. 2C).In these embodiments, after the formation of the connector 68,semiconductor devices 10 may be sawed apart, so that the semiconductordevices 10 are separated from each other. In some embodiments, in orderto saw the semiconductor devices 10, the plurality of semiconductordevices are attached on a dicing tape (not shown), and are diced whenattached to the dicing tape.

FIG. 3C illustrates bonding the second side 33 of the interconnectingstructure 30 to a second substrate 70 by way of bonding structures 74and the UBMs 22. The second substrate 70 and the contacts 72 may besimilar to the second substrate 70 and the contacts 58 described abovewith reference to FIG. 2G and the descriptions will not be repeatedherein. In an embodiment, the second substrate 70 may be bonded to theinterconnecting structure 30 by a reflow process. During this reflowprocess, the contacts 72 on the second substrate 70 are in contact withthe connectors 68 to form bonding structures 74 to physically andelectrically couple the second substrate 70 to the interconnectingstructure 30 via the UBMs 22.

The number of bonding structures 74, the number of contacts 72, thenumber of UBMs 46 and 22, and the number of connectors 50 in FIG. 3C areonly for illustrative purposes and are not limiting. There could be anysuitable number of UBMs 46 and 22, bonding structures 74, connectors 50,and contacts 72.

FIGS. 4A and 4B illustrate a semiconductor device 12 according toanother embodiment, wherein the connector on the UBM 22 of theinterconnecting structure 30 is formed by a solder ball drop method.Details regarding this embodiment that are similar to those for thepreviously described embodiment will not be repeated herein.

FIG. 4A illustrates a semiconductor device 12 with a photoresist 90 on apassivation layer 26, flux 92 on the UBM 22 (conductive pad 22), and asolder ball 98 on the flux 92. In an embodiment, the flux 92 may beformed on the UBM 22 by dipping the UBM 22 in flux so that flux 92 maybe deposited on the UBM 22 in the opening formed in the photoresist 90.In another embodiment, the flux 92 may be deposited as a paste and maybe printed on the UBM 22 and in the opening formed in the photoresist90. After the flux 92 is formed, a solder ball 98 is formed on the flux92. The solder ball 98 may be formed by a solder ball drop process. Thesolder ball drop process is known in the art, and thus, is not detailedherein.

FIG. 4B illustrates the formation of the connector 100. The connector100 may allow various other devices and/or substrates to be electricallycoupled to the second side 33 of the interconnecting structure 30 (seeFIG. 2I). The photoresist 90 may be removed through a suitable removalprocess such as ashing. The connector 100 is formed by performing areflow process on the solder ball 98 and the flux 92. The connector 100may cost less to form than the connector 68 of FIG. 3B. However, anembodiment with connector 68 may have better electrical migrationproperties than an embodiment with connector 100 due to intermetalliccompounds near an interface with UBM 22 of the connector 100 embodiment.The thermal cycling properties of the connector 100 are similar to thethermal cycling properties of the connector 68. In some embodiments, thefirst portion 30A of interconnecting structure 30 may also have aconnector 100 formed on the UBM 22.

FIG. 5 illustrates a semiconductor device 14 according to anotherembodiment, wherein the connector on the second side 33 of theinterconnecting structure 30 includes a polymer layer on the passivationlayer 26. Details regarding this embodiment that are similar to thosefor the previously described embodiment will not be repeated herein.

FIG. 5 illustrates a semiconductor device with a polymer layer 102 onthe passivation layer 26 and on a portion of a top surface of the UBM22. The polymer layer 102 may be formed of a polymer, such as an epoxy,polyimide, BCB, PBO, the like, or a combination thereof, although otherrelatively soft, often organic, dielectric materials can also be used.The polymer layer 102 may be formed by spin coating or other commonlyused methods. After the polymer layer 102 is formed on the passivationlayer 26 and the UBMs 22, an opening may be formed through the polymerlayer 102 to expose a portion of at least one UBM 22. A seed layer 104may be deposited along the polymer layer 102 and in the opening over theUBM 22 and a connector 106 may be formed on the seed layer 104 and inthe opening over the UBM 22. The seed layer 104 and the connector 106may be similar to the seed layer 62 and the connector 68 as describedabove with reference to FIGS. 3A and 3B and the description of them willnot be repeated herein.

FIG. 6 illustrates a flow diagram of a method 500 for manufacturing asemiconductor device in accordance with an embodiment. While method 500is illustrated and described below as a series of acts or events, itwill be appreciated that the illustrated ordering of such acts or eventsare not to be limited to a particular embodiment. For example, some actsmay occur in different orders and/or concurrently with other acts orevents apart from those illustrated and/or described herein. Inaddition, not all illustrated acts may be required to implement one ormore aspects or embodiments of the description herein. Further, one ormore of the acts depicted herein may be carried out in one or moreseparate acts and/or phases.

The operations of method 500 will be described with reference to FIGS.7A through 7C as an example, although the method 500 may be applied toother embodiments.

At operation 502, a conductive pad is formed in a first substrate. Atoperation 504, a passivation layer is formed over the conductive pad. Atoperation 506, an interconnecting structure is formed over thepassivation layer and the conductive pad. At operation 504 a connectoris formed over a first side of the interconnecting structure 30.Operations 502, 504, 506, 508, and 510 are illustrated in FIG. 7A asdescribed below.

FIG. 7A illustrates a semiconductor device 16 at an intermediate stageof processing according to an embodiment. The semiconductor device 16includes conductive pads 22 formed in a first substrate 20, apassivation layer 26 formed on a first substrate 20 and the conductivepads 22, pad connectors 24 formed in the passivation layer 26 andcontacting the conductive pads 22, an interconnecting structure 30formed on the passivation layer 26 and the pad connectors 24, first andsecond passivation layers 41 and 42 formed over the interconnectingstructure 30, UBMs 47A formed in openings and along the first and secondpassivation layers 41 and 42, connectors 50A formed over the secondpassivation layer 42 and in electrical contact with the first side 31 ofthe interconnecting structure, and a carrier 116 mounted to theconnectors 50A with an adhesive layer 114. UBMS 47A may be similar toUBMS 46 and connectors 50A may be similar to connectors 50 describedabove and the descriptions will not be repeated herein. Detailsregarding this embodiment that are similar to those for the previouslydescribed embodiment will not be repeated herein.

A carrier 116 may then be mounted to the connectors 50A through anadhesive layer 114. The adhesive layer 114 may be disposed, for examplelaminated, on the carrier 116. The adhesive layer 114 may be formed of aglue, such as an ultra-violet glue, or may be a lamination layer formedof a foil. The carrier 116 may be any suitable substrate that provides(during intermediary operations of the fabrication process) mechanicalsupport for the layers on top. The carrier 116 may comprise a wafercomprising glass, silicon (e.g., a silicon wafer), silicon oxide, metalplate, a ceramic material, or the like.

At operation 512, the first substrate is thinned. Operation 512 isillustrated in FIG. 7B as described below.

FIG. 7B illustrates the thinning of the first substrate 20. In FIG. 7B,the semiconductor device 16 has been flipped over so that the carrier116 is towards the bottom of the figure. The thinning process of thefirst substrate 20 may be similar to the process described above withreference to FIG. 2D and the description of them will not be repeatedherein.

At operation 514, the remaining portions of the first substrate 20 maybe removed. Operation 514 is illustrated in FIG. 7C.

FIG. 7C illustrates the removal of the remaining portion of the firstsubstrate 20 and to expose portions of UBM 22. The removal of theremaining portion of the first substrate 20 may be similar to theprocess described above with reference to FIG. 2E and the descriptionwill not be repeated herein.

At operation 516, a die is bonded to the second side of theinterconnecting structure. Operation 516 is illustrated in FIG. 7C asdescribed below.

FIG. 7C illustrates the bonding of the die 54 to the second side 33 ofthe interconnecting structure 30 by way of connectors 50B and UBMs 22with an underfill material 52 between the die 54 and the passivationlayer 26. The UBMs 22 may be similar to the UBMs 22 described above withreference to FIGS. 2F through 2I and the description will not berepeated herein. The die 54 and the process of bonding the die to theinterconnecting structure 30 were described above with reference to FIG.2A and the description of them will not be repeated herein. Theconnectors 50B may be similar to connectors 50 described above and thedescription will not be repeated herein, although connectors 50A andconnectors 50B need not be the same.

At operation 518, the first side of the interconnecting structure may bebonded to a second substrate. Operation 518 may be similar to theprocess described above with reference to FIG. 2I except that thisoperation bonds the first side 31 of the interconnecting structure 30 tothe second substrate rather than the second side 33 of theinterconnecting structure 30 as described above. Thus, the descriptionof this operation will not be repeated herein.

By having an interconnecting structure 30 coupling the die 54 to thesecond substrate 70, the cost of the semiconductor device 10 may be muchlower than other devices. Because the interconnecting structure 30 doesnot have a substrate, through substrate vias (TSVs) are not necessary tocouple the die 54 to the second substrate 70, and TSVs are a significantcost in other devices. Further, because the process does not require acarrier wafer or the formation of backside connectors, the cost of thedevices may be reduced. However, the yield, reliability, and performanceof the interconnecting structure 30 are not impacted by the removal ofthe substrate and/or the lack of TSVs. Rather, the reliability may beenhanced due to the omission of the TSVs and the formation of backsideconnectors.

An embodiment is a method of forming a semiconductor device, the methodcomprising forming a conductive pad in a first substrate, forming aninterconnecting structure over the conductive pad and the a firstsubstrate, the interconnecting structure comprising a plurality of metallayers disposed in a plurality of thin film dielectric layers, bonding adie to a first side of the interconnecting structure, and etching thefirst substrate from a second side of the interconnecting substrate, theetching exposing a portion of the conductive pad.

Another embodiment is a method of forming a semiconductor device, themethod comprising forming a conductive pad in a top surface of a firstsubstrate, forming a passivation layer over the top surface of the firstsubstrate and the conductive pad, forming pad connectors in thepassivation layer contacting the conductive pad, forming aninterconnecting structure over the passivation layer and pad connectors,forming a first structure over the interconnecting structure, andremoving the first substrate to expose the conductive pad.

A further embodiment is a method of forming a semiconductor device, themethod comprising forming a conductive pad in a top surface of a firstsubstrate, forming a passivation layer over the top surface of the firstsubstrate and the conductive pad, forming pad connectors in thepassivation layer contacting the conductive pad, forming a plurality ofthin film layers and a plurality of metal layers disposed therein overthe passivation layer and the pad connectors, at least one of theplurality of metal layers contacting the pad connectors, bonding a dieto at least one of the plurality of metal layers, and thinning a bottomsurface of the first substrate to expose the conductive pad.

Although the present embodiments and their advantages have beendescribed in detail, it should be understood that various changes,substitutions, and alterations can be made herein without departing fromthe spirit and scope of the disclosure as defined by the appendedclaims. Moreover, the scope of the present application is not intendedto be limited to the particular embodiments of the process, machine,manufacture, composition of matter, means, methods, and operationsdescribed in the specification. As one of ordinary skill in the art willreadily appreciate from the disclosure, processes, machines,manufacture, compositions of matter, means, methods, or operations,presently existing or later to be developed, that perform substantiallythe same function or achieve substantially the same result as thecorresponding embodiments described herein may be utilized according tothe present disclosure. Accordingly, the appended claims are intended toinclude within their scope such processes, machines, manufacture,compositions of matter, means, methods, or operations.

What is claimed is:
 1. A semiconductor device comprising: aninterconnecting structure consisting of a plurality of dielectric layersand a plurality of metal layers disposed therein; a die comprising anactive surface and a backside surface opposite the active surface, theactive surface being coupled to a first side of the interconnectingstructure; a passivation layer on a second side of the interconnectingstructure, the second side being opposite the first side, thepassivation layer having a first surface proximate the second side ofthe interconnecting structure, and a second surface distal the secondside of the interconnecting structure; and a conductive pad on thepassivation layer and coupled to the second side of the interconnectingstructure, a third surface of the conductive pad being substantiallycoplanar with the second surface of the passivation layer, the thirdsurface of the conductive pad being substantially parallel to the activesurface of the die.
 2. The semiconductor device of claim 1 furthercomprising a substrate bonded to the conductive pad with a firstconnector.
 3. The semiconductor device of claim 2, wherein the firstconnector comprises solder.
 4. The semiconductor device of claim 2,wherein the first connector comprises copper, aluminum, gold, nickel,silver, tin, or a combination thereof.
 5. The semiconductor of claim 2,wherein the first connector comprises an under bump metallization (UBM),the UBM directly contacting the conductive pad.
 6. The semiconductordevice of claim 1, wherein the active surface of the die is coupled tothe first side of the interconnecting structure with a second connector.7. The semiconductor device of claim 6, wherein the second connectorcomprises a solder ball, a metal pillar, a micro bump, or a controlledcollapse chip connection bump.
 8. The semiconductor device of claim 7,wherein the second connector further comprises a UBM.
 9. Thesemiconductor device of claim 1 further comprising a molding compoundsurrounding the die, a portion of the molding compound extending overthe backside surface of the die.
 10. The semiconductor device of claim1, wherein the plurality of metal layers of the interconnectingstructure further comprises: a plurality of metal trenches and aplurality of vias, each of the plurality of vias extending through atleast one of the plurality of dielectric layers to couple at least twoof the plurality of trenches.
 11. A semiconductor device comprising: aconductive pad; a plurality of pad connectors over and contacting theconductive pad, the plurality of pad connectors being disposed in apassivation layer, the plurality of pad connectors having a firstthickness as measured in first direction, the first direction beingsubstantially perpendicular to a major surface of the passivation layer,the passivation layer having the first thickness as measured in thefirst direction; a plurality of thin film layers and a plurality ofmetal layers disposed therein over the passivation layer and the padconnectors, at least one of the plurality of metal layers contacting thepad connectors; and a die directly coupled to at least one of theplurality of metal layers.
 12. The semiconductor device of claim 11further comprising a substrate bonded to the conductive pad with a firstconnector.
 13. The semiconductor device of claim 12, wherein the firstconnector comprises solder, copper, aluminum, gold, nickel, silver, tin,or a combination thereof.
 14. The semiconductor device of claim 11,wherein the die is coupled to the at least one of the plurality of metallayers with a second connector.
 15. The semiconductor device of claim14, wherein the second connector comprises a solder ball, a metalpillar, a micro bump, or a controlled collapse chip connection bump. 16.The semiconductor device of claim 11, wherein the die is directlycoupled to a different metal layer than the at least one of theplurality of metal layers contacting the pad connectors.
 17. Asemiconductor device comprising: an interconnecting structure, theinterconnecting structure comprising: a first metal layer disposed in afirst dielectric layer, the first metal layer having a first surfacesubstantially coplanar with a first side of the interconnectingstructure; a second metal layer disposed in a second dielectric layer,the second metal layer having a second surface substantially coplanarwith a second side of the interconnecting structure, the second sidebeing opposite the first side; and a plurality of metal layers extendingfrom the first metal layer to the second metal layer, each metal layerof the plurality of metal layers being disposed in a dielectric layer; adie comprising an active surface and a backside surface opposite theactive surface, the active surface coupled to the first side of theinterconnecting structure; a passivation layer adjacent the second sideof the interconnecting structure, the passivation having a firstthickness with a third surface of the passivation layer being the firstthickness from the second side of the interconnecting structure, thefirst surface being substantially parallel to the second side of theinterconnecting structure; and a conductive pad adjacent the passivationlayer and coupled to the second side of the interconnecting structure,the passivation layer being interposed between the conductive pad andthe second side of the interconnecting structure, the conductive padextending along and contacting the third surface of the passivationlayer.
 18. The semiconductor device of claim 17 further comprising padconnectors in the passivation layer, the pad connectors coupling theconductive pad to the second metal layer.
 19. The semiconductor deviceof claim 18 further comprising a substrate bonded to the conductive padwith a first connector, wherein the first connector comprises solder,copper, aluminum, gold, nickel, silver, tin, or a combination thereof.20. The semiconductor device of claim 17, wherein the die is coupled tothe first metal layer with a second connector, wherein the secondconnector comprises a solder ball, a metal pillar, a micro bump, or acontrolled collapse chip connection bump.